Conventional sewing controllers of embroidery sewing machines pre-store embroidery data for various patterns such as decorative stitch patterns and one-point patterns. When sewing such embroidery patterns with different colors, a user is first required to select the desired pattern from various types of pre-stored embroidery patterns shown on a display. Subset patterns, each representing a different thread color, are sewn by replacing the needle thread to the required thread color. When executing a sewing operation with an embroidery sewing machine having only one needle bar, a troublesome task of needle thread replacement is required every time sewing of a subset pattern representing a single color has been completed. Such requirement inefficiently prolongs the duration of sewing operation.
To address the above problem, it has been recently proposed to use multiple sets of embroidery sewing machines having a single needle bar to sew an embroidery pattern with different colors. That is, an embroidery pattern comprising different thread colors is sewn simultaneously by using multiple sets of embroidery sewing machines having a single needle bar. Alternatively, an embroidery pattern comprising different thread colors may be sewn at once by a multi-needle embroidery sewing machine provided with multiple needle bars without having to replace the needle thread.
A sewing system capable of multi-color pattern sewing described in JP S59-82891 A comprise four sets of sewing machines each connected to a main controller. Each sewing machine is responsible for sewing with a single type of thread (single color of thread), in this case, sewing machine 1 is assigned the color “red”, sewing machine 2 is assigned the color “yellow”, sewing machine 3 is assigned the color “green”, and sewing machine 4 is assigned the color “blue”.
When sewing a pattern comprising the four colors namely red, yellow, green, and blue stored in the main controller, the data corresponding to each color is transmitted separately to each sewing machine from the main controller. More specifically, sewing thread-color data and location data group for the color “red” is transmitted to sewing machine 1, the same for “yellow” to sewing machine 2, the same for “green” to sewing machine 3, and the same for “blue” to sewing machine 4. Thus, each of sewing machines 1 to 4 sews the assigned embroidery pattern subset (red subset, yellow subset, green subset, and blue subset) at the same time.
As another example, JP H09-111638A discloses a sewing data processor capable of displaying an embroidery pattern that efficiently utilizes idle time available until thread replacement. When sewing an embroidery pattern with an embroiderable sewing machine disclosed in JP H09-111638 A, an embroidery pattern is selected among a plurality of embroidery patterns shown on a display, the embroidery pattern comprising a plurality of subset patterns of different thread colors. The sewing data processor calculates the sew time required for embroidering each of the subset patterns based on pattern data representing the selected embroidery pattern. Sewing data processor displays the required sew time for each subset pattern on the display. Thus, JP H09-111638 A allows the user to efficiently direct the idle time available before the next thread replacement to other activities.
Yet, as another example, production management system for embroidery sewing device described in JP-H11-253676 A calculates time period required for sewing a single lot unit of embroidery patterns, comprising groups of embroidery sub-patterns, based on pattern data of the embroidery pattern to be sewn and data on count of patterns constituting the single lot unit. Then the production management system allocates the lot to either of embroidery sewing machines M1 to M4 based on data indicating the calculated time period required for sewing the lot. The production management system, then, shows the required time period for sewing each lot allocated to each of the embroidery sewing machines M1 to M4 on a display.
Still yet as another example, JP H06-304372 A discloses a sewing system including first and second automatic sewing machines. The first automatic sewing machine includes a RAM for storing sewing data, a data editor for editing sewing data and restoring the edited data in the RAM, and a data transmitter for transmitting the edited data to the second automatic sewing machine. The second automatic sewing machine executes sewing operation based on the incoming data transmitted from the data transmitter of the first automatic sewing machine.
JP S59-82891 A sews an embroidery pattern with multiple sets of sewing machines having a single needle bar. Thus when sewing an embroidery pattern having ten different colors of subset patterns, a dedicated sewing machine is required for each thread color, amounting to ten sewing machines, and therefore requiring large spacing. Also, when size of subset pattern varies color by color, little time is required for sewing small subset patterns while greater time is required for sewing larger subset patterns, leading to reduced capacity usage of sewing machines having relatively shorter sew time.
JP H09-111638 A merely displays sew time required for each subset pattern for the selected embroidery pattern. Thus, the sew time required for each subset pattern is not utilized for effective control of the sewing operation such as sewing subset patterns in the sequence of shortest to longest sew time or vice versa.
JP H11-253676 A manages amount of sewing work in units of lots, and lots are allocated one by one to either of embroidery sewing machines M1 to M4 so that no single lot is sewn by multiple sewing machines. Such arrangement may create instances where lots are distributed unevenly to embroidery sewing machines M1 to M4, resulting in vast difference in sew time between the sewing machines M1 to M4, which renders work scheduling difficult.
JP H06-304372 A merely transmits sewing data stored in a RAM of a first automatic sewing machine to a second automatic sewing machine and simply executes the same or different work simultaneously without any scheduling features. Thus, sewing work amount and time may very well differ between the first and the second automatic sewing machines.